package com.hmdp.service.impl;

import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    /**
     * 秒杀优惠券
     *
     * @param voucherId
     * @return
     */
    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private RedissonClient redissonClient;

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;//提前读好，如果在执行状态下去读脚本会产生IO流，影响效率
    //DefaultRedisScript是RedisScript的一个实现类
    //泛型是返回值类型，返回的是一个数值所以用long

    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();//也可以直接用硬编码方式掺入一个字符串（不推荐）
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));//设置脚本位置，
        SECKILL_SCRIPT.setResultType(Long.class);//配置返回值类型
    }
    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024);
    private static ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    @PostConstruct//在容器初始化完成后执行
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    private class VoucherOrderHandler implements Runnable {
        @Override
        public void run() {
            while (true) {
                try {
                    //1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (InterruptedException e) {
                    log.error("处理订单异常",e);
                }
            }
        }
    }

    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        //获取锁对象
        //SimpleRedisLock lock = new SimpleRedisLock("order:"+userId, stringRedisTemplate);
        Long userId = voucherOrder.getUserId();
        RLock lock = redissonClient.getLock("lock:order:" + userId);

        //获取锁
        boolean isLock = lock.tryLock();
        //判断是否获取锁成功
        if (!isLock) {
            //获取锁失败，返回错误信息，重试
            log.error("用户{}重复下单",userId);
        }
        try {
            proxy.createVoucherOrder(voucherOrder);
        } catch (IllegalStateException e) {
            throw new RuntimeException(e);
        }finally {
            //释放锁
            lock.unlock();
        }
    }
    /*@Override
    public Result seckillVoucher(Long voucherId) {
        // 1.查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        // 1.1判断优惠券是否存在
        //1.2优惠券不存在
        if (voucher == null) {
            return Result.fail("优惠券不存在");
        }

        //2.判断秒杀是否开始
        //2.1秒杀未开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            return Result.fail("秒杀未开始");
        }
        //2.2秒杀已经结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            return Result.fail("秒杀已经结束");
        }

        //3.判断库存是否充足
        //3.1库存不足
        if (voucher.getStock() <= 0) {
            return Result.fail("库存不足");
        }
        Long userId = UserHolder.getUser().getId();

        //获取锁对象
        //SimpleRedisLock lock = new SimpleRedisLock("order:"+userId, stringRedisTemplate);

        RLock lock = redissonClient.getLock("lock:order:" + userId);

        //获取锁
        boolean isLock = lock.tryLock();
        //判断是否获取锁成功
        if (!isLock) {
            //获取锁失败，返回错误信息，重试
            return Result.fail("不允许重复下单");
        }
        try {
            //获取带对象（事务）
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        } catch (IllegalStateException e) {
            throw new RuntimeException(e);
        }finally {
            //释放锁
            lock.unlock();
        }
    }*/

    private IVoucherOrderService proxy;

    @Override
    public Result seckillVoucher(Long voucherId) {
        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                UserHolder.getUser().getId().toString()
        );
        //2.判断结果是否为0
        int r = result.intValue();
        if (r != 0) {
            //2.1不为0，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        //2.2为0，有购买资格，把下单信息保存到阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        //2.3订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //2.4用户id
        voucherOrder.setUserId(UserHolder.getUser().getId());
        //2.5优惠券id
        voucherOrder.setVoucherId(voucherId);
        //2.6放入阻塞队列
        orderTasks.add(voucherOrder);
        //2.7获取代理对象
        //获取带对象（事务）
        IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
        //3.返回订单id
        return Result.ok(orderId);
    }

    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        //3.2库存充足
        //4一人一单
        Long userId = voucherOrder.getUserId();
        //4.1查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        //4.2判断是否存在
        if (count > 0) {
            //4.3用户已经购买过了
            log.error("用户{}已经购买过一次",userId);
            return;
        }
        //5.扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")//set stock = stock - 1
                .eq("voucher_id", voucherOrder.getVoucherId())//
                .gt("stock", 0)//where stock = 10
                .update();
        //5.1扣减失败
        if (!success) {
            log.error("扣减库存失败");
            return ;
        }
        //7.保存订单
        save(voucherOrder);
    }
}
